The applicant, the Lead Center in the current Herpetic Eye Diseases Study (HEDS), proposes to be the Lead Center and a Regional Center for Phase II of HEDS. Phase II will consist of two randomized, double-masked clinical trials and a non-experimental study of trigger factors of recurrence of ocular herpetic diseases. The HEDS group now proposes to evaluate oral acyclovir for the prevention of herpetic stromal keratitis and iridocyclitis and the suppression of recurrences. One new HEDS protocol will evaluate oral acyclovir given during acute herpetic epithelial keratitis for preventing stromal keratitis and iridocyclitis (Herpetic Eye Disease Study - Epithelial Keratitis Trial: HEDS-EKT). A second protocol will evaluate the efficacy of oral acyclovir for preventing recurrent episodes of herpetic eye disease (Herpetic Eye Diseases Study - Acyclovir Prevention Trial - HEDS-APT). A third study of biological and psychological risk factors for recurrences of herpetic eye disease (Herpetic Eye Disease - Risk Factor Study: HEDS RFS) will determine the importance of these factors among patients in the two clinical trials. The studies will utilize a community-based clinical trial design and include eight regional centers with five to 11 participating sites each. The Lead Center will develop and carry out training programs for the Regional and Participating Centers, certify and monitor Regional Centers, act as the executive center, and participate in the overall governance of HEDS by participation in all HEDS committees. As a Regional Center, the applicant will enter patients in the two clinical trials according to protocol and will enter randomized patients into the triggers study. It will coordinate and oversee the participation of 11 additional participating local sites in the APT and EKT trials.